High throughput wafer notch aligner

ABSTRACT

An ion implantation apparatus, system, and method are provided for a transferring a plurality of workpieces between vacuum and atmospheric pressures, wherein an alignment mechanism is operable to align a plurality of workpieces for generally simultaneous transportation to a dual-workpiece load lock chamber. The alignment mechanism comprises a characterization device, an elevator, and two vertically-aligned workpiece supports for supporting two workpieces. First and second atmospheric robots are configured to generally simultaneously transfer two workpieces at a time between load lock modules, the alignment mechanism, and a FOUP. Third and fourth vacuum robots are configured to transfer one workpiece at a time between the load lock modules and a process module.

FIELD OF THE INVENTION

The present invention relates generally to workpiece processing systemsand methods for processing workpieces, and more specifically to a systemand method for handling and aligning workpieces wherein throughput ismaximized.

BACKGROUND OF THE INVENTION

In semiconductor processing, many operations may be performed on asingle workpiece or semiconductor wafer. In general, each processingoperation on a workpiece is typically performed in a particular order,wherein each operation waits until completion of a preceding operation,thus affecting the time at which the workpiece will become available fora subsequent processing step. Tool productivity or throughput forrelatively short processes performed under vacuum, such as ionimplantation, can be severely limited if the process flow leading to theprocessing location is interrupted by sequential events associated withsuch processing. For example, operations such as an exchange ofworkpieces between transport carriers or storage cassettes and theprocessing system, a transfer of the workpiece from an atmosphericenvironment into an evacuated environment of an implantation chamber ofthe processing system, and an orientation of the workpiece (e.g., notchalignment) within the evacuated environment, can have a significantimpact on tool productivity.

Processing of a workpiece, such as ion implantation, for example, istypically performed at a reduced pressure within an implantationchamber, wherein ions are generally accelerated along a beam line, andwherein the ions enter the evacuated implantation chamber and strike theworkpiece in a predetermined manner. Several operations are typicallyperformed leading up to the implantation in order to introduce theworkpiece into the implantation chamber, as well as to properly positionand orient the workpiece with respect to the ion beam within the ionimplantation chamber. For example, the workpiece is transferred via arobot from an atmospheric cassette or storage device into a load lockchamber, wherein the load lock chamber is subsequently evacuated inorder to bring the workpiece into the processing environment of the ionimplanter. The cassette or storage device, for example, may be deliveredto the ion implanter via a conveyor system or other type of delivery.

Front opening unified pods (FOUPs), for example, have become a popularmechanism for moving silicon workpieces or wafers from one workstationto another in an integrated circuit (IC) fabrication facility. Differentversions of these FOUPs are commercially available from differentmanufacturers, including Asyst Technologies and Brooks Automation. AFOUP containing a number of stacked wafers, for example, is deliveredfrom one tool to a next subsequent tool by an automated delivery devicesuch as an overhead transport. The overhead transport deposits the podto a location within the reach of a robot so that a robotic arm canextract one or more silicon wafers from the pod for treatment.

U.S. Pat. No. 5,486,080 to Sieradzki, for example, details a system fortransferring wafers for vacuum processing. The system employs two wafertransport robots for moving wafers from two load locks past a processingstation. Additional patents relating to serial end stations are U.S.Pat. Nos. 6,350,097, 6,555,825, and 5,003,183. Further, commonly-ownedU.S. Pat. No. 7,010,388 to Mitchell et al. details a wafer handlingsystem for handling one or two wafers at a time.

It is desirable for the workpiece handling system to have very highthroughputs in order to reduce the tool's cost of ownership. This isespecially true in an ion implantation process when a duration of theimplantation is very short compared to the time needed to transfer a newworkpiece from the FOUP to the process chamber and back to the FOUP. Theactual ion implantation into a workpiece for a low dose implant, forexample, has a short duration, wherein implant times can be less than 5seconds. Further, as part of pre-processing routines utilized in ionimplantation, each workpiece must be oriented properly relative to theion beam. A mechanism known as an aligner is used for such an alignmentstep, where each workpiece is aligned serially, thus potentiallydecreasing throughput.

Therefore, a need exists for a system and method for facilitating highthroughput by allowing simultaneous placement of two workpieces by anatmospheric wafer handling robot at the aligner station for subsequentserial alignment by the aligner mechanism. Since two wafers can bedropped off simultaneously, the atmospheric wafer handling robot canproceed onto other tasks which allow the wafer robot to handle morewafers per hour.

SUMMARY OF THE INVENTION

The present invention overcomes the limitations of the prior art byproviding a system, apparatus, and method for transferring workpiecesbetween atmospheric and vacuum environments, while maximizing throughputand minimizing costs of ownership associated with the systems. Moreparticularly, the present invention provides a system and method forreducing a cost of ownership of the system by minimizing an idle time,or the amount of time a processing system is operating but not producinga processed workpiece.

Accordingly, the following presents a simplified summary of theinvention in order to provide a basic understanding of some aspects ofthe invention. This summary is not an extensive overview of theinvention. It is intended to neither identify key or critical elementsof the invention nor delineate the scope of the invention. Its purposeis to present some concepts of the invention in a simplified form as aprelude to the more detailed description that is presented later.

The present invention is directed generally toward a workpiece handlingsystem and method for handling workpieces, and an alignment apparatusand method for using same. In accordance with one exemplary aspect ofthe invention, the workpiece handling system comprises one or moreworkpiece transport containers configured to support a plurality ofworkpieces, and a front end module in selective engagement with theworkpiece transport container(s). In one example, the front end modulecomprises a first robot having a first dual-workpiece handling armoperably coupled thereto, a second robot having a second dual-workpiecehandling arm operably coupled thereto, and an alignment mechanismdisposed generally therebetween. The alignment mechanism comprises acharacterization device, an elevator mechanism, and two or morevertically-aligned workpiece supports configured to respectivelyselectively support two or more of the plurality of workpieces. Theelevator mechanism is operable to both rotate and translate verticallywith respect to an axis associated therewith, and the two or moreworkpiece supports are operable to translate radially with respect tothe axis. The elevator mechanism is thus operable to individuallyvertically translate each workpiece from the respective workpiecesupports to a characterization position, wherein the elevator mechanismis further operable to determine one or more characteristics of each ofthe plurality of workpieces at the characterization position, such as arotational position and/or center of each workpiece via the rotation ofthe workpiece with respect to the characterization device.

The system further comprises a vacuum chamber having a third robot and afourth robot disposed therein, wherein the third robot comprises a firstsingle-workpiece handling arm operably coupled thereto, and the fourthrobot comprises a second single-workpiece handling arm operably coupledthereto. A processing module is further operably coupled to the vacuumchamber for processing the plurality of workpieces through a processmedium, such as an ion beam. First and second load lock modules areoperably coupled to both the front end module and the vacuum chamber,wherein each of the first and second load lock modules comprise two ormore dual-workpiece load lock chambers configured to respectivelysupport two or more workpieces therein. For example, first, second,third, and fourth dual-workpiece load lock chambers are provided,wherein the first load lock module comprises the first and third loadlock chambers, and the second load lock module comprises the second andfourth load lock chambers, wherein each of the first, second, third, andfourth load lock chambers are configured to support the two or more ofthe plurality of workpieces therein.

In accordance with one exemplary aspect, the first robot is configuredto selectively transfer one or more workpieces at a time (e.g.,concurrently transfer two workpieces in parallel) between the workpiecetransport container, the alignment mechanism, and the second load lockmodule via the first dual-workpiece handling arm. The second robot isfurther configured to selectively transfer one or more workpieces at atime (e.g., concurrently transfer two workpieces in parallel) betweenanother workpiece transport container, the alignment mechanism, and thefirst load lock module via the second dual-workpiece handling arm. Thethird robot is configured to selectively serially transfer one workpieceat a time between the first load lock module and the process module viathe first single-workpiece handling arm, and the fourth robot isconfigured to selectively serially transfer one workpiece at a timebetween the second load lock module and the process module via thesecond single-workpiece handling arm. A controller is further provided,wherein the controller is configured to selectively transfer theplurality of workpieces between the workpiece transport container,alignment mechanism, first and second load lock modules, and processmodule via a control of the first, second, third, and fourth robots,alignment mechanism, and first and second load lock modules.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of a few of thevarious ways in which the principles of the invention may be employed.Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a block diagram of an exemplary workpiece handlingsystem in accordance with one aspect of the present invention.

FIG. 1B illustrates the exemplary workpiece handling system of FIG. 1Ahaving a reverse workpiece flow.

FIG. 2 illustrates schematic of an exemplary workpiece handling systemin accordance with another aspect of the present invention.

FIG. 3A illustrates a perspective view of an exemplary alignmentmechanism according to another aspect of the present invention.

FIG. 3B illustrates a plan view of the exemplary alignment mechanism ofFIG. 3A.

FIGS. 4A-4F illustrate the exemplary alignment mechanism of FIGS. 3A and3B during various stages of workpiece alignment according to anotherexemplary aspect of the invention.

FIG. 5 is a partial cross-sectional view of the exemplary alignmentmechanism of FIGS. 3A and 3B.

FIG. 6 is a plan view of an exemplary workpiece on a workpiece supportof an exemplary alignment mechanism.

FIG. 7 is plot of a sensed position of a workpiece versus a rotationalposition of the workpiece support according to another exemplary aspectof the invention.

FIG. 8 is a perspective view of an exemplary load lock module accordingto yet another aspect of the present invention.

FIG. 9 illustrates another exemplary workpiece handling system accordingto still another aspect of the invention.

FIG. 10A illustrates a bottom plan view of an exemplary dual-workpiecehandling robot of FIG. 9.

FIG. 10B illustrates an elevation view of the exemplary dual-workpiecehandling robot of FIG. 10A.

FIG. 11 is a block timing diagram for handling workpieces according toanother exemplary aspect of the invention.

FIG. 12 is a block diagram illustrating an exemplary method for handlingworkpieces according to another exemplary aspect of the invention.

FIG. 13 is a block diagram illustrating a continuation of the exemplarymethod of FIG. 12 for handling workpieces according to another aspect ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed generally toward a workpiece handlingsystem for semiconductor processes, and more particularly, to a handlingsystem wherein two or more workpieces can be transferred within thesystem generally simultaneously, while still achieving serial operationssuch as alignment and ion implantation into the workpiece. Accordingly,the present invention will now be described with reference to thedrawings, wherein like reference numerals may be used to refer to likeelements throughout. It should be understood that the description ofthese aspects are merely illustrative and that they should not beinterpreted in a limiting sense. In the following description, forpurposes of explanation, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be evident to one skilled in the art, however, that the presentinvention may be practiced without these specific details.

Referring now to the figures, FIGS. 1A and 1B illustrate an exemplaryworkpiece handling system 100 in accordance with one exemplary aspect ofthe present invention. The workpiece handling system 100, for example,comprises a front end module 102, wherein the front end module comprisesone or more load ports 104A-104D operable to receive one or moreworkpiece transport containers 106A-106D. Each of the load ports104A-104D, for example, comprises a door 107A-107D operable to provideselective communication between the respective workpiece transportcontainers 106A-106D and the front end module 102. The workpiecetransport containers 106A-106D, for example, comprise Front OpeningUnified Pods (FOUPs) 108, wherein each FOUP is operable to interfacewith the front end module 102. An internal environment 109 of the frontend module 102, for example, is generally at or near atmosphericpressure.

The front end module 102 comprises a first robot 110 and a second robot112, wherein, for example, the first robot is operable to load andunload a plurality of workpieces 114 (e.g., 300 mm semiconductor wafers)from the workpiece transport containers 106A and 106B, and the secondrobot is operable to load and unload a plurality of workpieces from theworkpiece transport containers 106C and 106D. Each of the first andsecond robots 110 and 112, for example, are capable of multiple degreesof freedom including vertical, radial and azimuthal movements.

As illustrated in greater detail in FIG. 2, in accordance with thepresent invention, the first robot 110 comprises a first dual-workpiecehandling arm 116 operably coupled thereto, wherein the firstdual-workpiece handling arm, for example, comprises a first dual supportmember 118 operable to support one or multiple workpieces 114 thereon.For example, the first dual-workpiece handling arm 116 is configured toconcurrently or generally simultaneously retrieve and replace two of theplurality of workpieces 114 from and to the workpiece transportcontainers 106A and 106B via a control of the first robot 110. The firstdual-workpiece handling arm 116, for example, may be further operable tosupport a single workpiece 114, as opposed to supporting multipleworkpieces. The second robot 112, for example, comprises a seconddual-workpiece handling arm 120 operably coupled thereto, wherein thesecond dual-workpiece handling arm is likewise configured tosimultaneously retrieve and replace two of the plurality of workpieces114 from and to the workpiece transport containers 106C and 106D via acontrol of the second robot. For example, the second dual-workpiecehandling arm 120 comprises a second dual support member 121 operable tosupport one or multiple workpieces 114 thereon. In a similar manner tothe first dual-workpiece handling arm 116, the second dual-workpiecehandling arm 120 may be further operable to support a single workpiece114, as opposed to supporting multiple workpieces.

The front end module 102 of the present invention, as illustrated inFIGS. 1A-1B and FIG. 2 further comprises an alignment mechanism 122disposed generally between the first and second robots 110 and 112,wherein the alignment mechanism is operable to determine one or morecharacteristics of the plurality of workpieces 114. FIG. 3A illustratesa perspective view of the exemplary alignment mechanism 122, wherein twoor more vertically-aligned workpiece tray stations 124A and 124B areprovided, and wherein each of the tray stations further comprise two ormore workpiece supports 126 associated therewith. The two or moreworkpiece supports 126 associated with each workpiece tray station 124Aand 124B, for example, are operable to support a respective workpiece114, as illustrated in phantom in a top view 127 of the alignmentmechanism 122 in FIG. 3B. The two or more workpiece tray stations 124Aand 124B of FIG. 3A, for example, further generally define two or morerespective buffer positions 128A and 128B, wherein the two or morebuffer positions provide a buffering or cueing of the plurality ofworkpieces 114 of FIGS. 1A-1B and FIG. 2 via the alignment mechanism122, as will be discussed in greater detail hereafter. It should benoted that the alignment mechanism 122 may comprise more than twoworkpiece tray stations 124 and buffer positions 128, and such multipleworkpiece tray stations and buffer positions are contemplated as fallingwithin the scope of the present invention.

In the present example, as illustrated in FIG. 3B, each of the workpiecesupports 126 associated with the respective workpiece tray stations 124Aand 124B are further associated with a circumference or perimeter 130 ofthe plurality of workpieces 114. For example, the plurality of workpiecesupports 126 are generally arcuate in shape, and have a recess 131formed therein, wherein the recess is configured to generally supportthe workpiece 114 about at least a portion of its circumference 130. Theplurality of workpiece supports 126 may alternatively take a number ofother forms, such as supporting posts or prongs (not shown).Accordingly, any member operable to support the workpiece 114 iscontemplated as falling within the scope of the present invention.

The plurality of workpiece supports 126 of the present example arefurther translationally coupled to a base 132 of the alignment mechanism122, wherein the plurality of workpiece supports are further operable toradially translate (as indicated by arrows 134) with respect to theworkpiece 114 and the base. Accordingly, the plurality of workpiecesupports 126 of each of the workpiece tray stations 124A and 124B areoperable to translate between a retracted position 136 (as illustratedin FIG. 4A for workpiece tray station 124A, and an extended position 137(as illustrated in FIG. 4C for workpiece tray station 124A). Theworkpiece tray stations 124A and 124B are individually configured suchthat their respective workpiece supports 126 may be selectively arrangedto either support the workpiece 114, or to generally permit theworkpiece to move freely vertically with respect to the workpiecesupports. The plurality of workpiece tray stations 124A and 124B arethus operable to selectively support each workpiece 114A and 114Billustrated in FIGS. 4A-4F, based on the respective plurality ofworkpiece supports being in the retracted position 136 or the extendedposition 137, as will be further described infra.

As illustrated in FIG. 3A, the alignment mechanism 122 further comprisesan elevator device 138 operably coupled to the base 132, wherein theelevator device is configured to individually vertically translate eachof the two or more workpieces 114A and 114B (shown in FIGS. 4A-4F)associated with the workpiece tray stations 124A and 124B. The alignmentmechanism 122 and elevator device 138 of FIG. 3A are further illustratedin a cross-sectional view 139 in FIG. 5, wherein the exemplary elevatordevice comprises an elevator shaft 140 operably coupled to an elevatorworkpiece support 142. The elevator shaft 140, for example, is in linearsliding engagement with the base 132, wherein the elevator workpiecesupport 142 is thus operable to selectively support each of theplurality of workpieces 114A and 114B (e.g., illustrated in FIGS. 4A-4F)based on a presence or absence of the plurality of workpieces andposition of the workpiece supports 126 of each tray station 124A and124B.

The elevator workpiece support 142, as illustrated in FIGS. 3A, 3B, and5 for example, comprises a vacuum chuck 144, wherein one or moreconduits 145 are operable to selectively provide a vacuum to a surface146 of the vacuum chuck for selectively gripping each workpiece 114. Asan alternative, the elevator workpiece support 142 may comprise pins(not shown), or other mechanisms operable to selectively individuallysupport each of the plurality of workpieces 114A and 114B of FIGS.4A-4F.

As illustrated in FIG. 5, the elevator shaft 140 is configured tolinearly translate along an axis 147 thereof, wherein, for example, theelevator shaft is operably coupled to a piston and cylinder assembly148. The piston and cylinder assembly 148, for example, is fluidlycoupled to a pressure source (not shown), wherein the piston andcylinder assembly can be selectively actuated, such as by pneumaticpressure, as will be understood by one of ordinary skill in the art.Alternatively, the elevator shaft 140 can be operably coupled to alinear motor (not shown), or other mechanism operable to selectivelyvertically translate the elevator shaft.

An exemplary operation of the elevator device 138 of the presentinvention is illustrated in FIGS. 4A-4F, wherein the elevator device isoperable to individually translate the two or more workpieces 114A and114B between the respective buffer positions 128A and 128B associatedwith each workpiece tray station 124A and 124B and a characterizationposition 150 (e.g., as illustrated in FIG. 4D) for characterization ofthe respective workpieces. In order to translate the two or moreworkpieces 114A and 114B from each workpiece tray station 124A and 124B,each workpiece is generally lifted from the workpiece supports 126 whenthe respective workpiece tray station is in the retracted position 136of 4A, for example, therein generally permitting the workpiece supportsof the respective tray station to be radially translated to the extendedposition 137, such as illustrated in FIGS. 4C and 4F. Once therespective tray station 124A and/or 124B are in the extended position137, the workpieces 124A or 124B may be vertically translated via theelevator device 138 to the characterization position 150.

According to one example, a horizontal translation device 152illustrated in FIG. 5 is operably coupled to each of the workpiecesupports 126 of the respective workpiece tray stations 124A and 124B,wherein the horizontal translation device is operable to selectivelyradially translate the respective workpiece support(s) between theretracted position(s) 136 and the extended position(s) 137 of FIGS.4A-4F. The extended position 137 illustrated in FIG. 4C associated withworkpiece tray station 124A, for example, is located beyond thecircumference 130 of the workpieces 114A and 114B. The elevator device138 is therefore operable to solely support and vertically translate therespective workpiece 114A and 114B when the respective workpiece traystation 124A and 124B is in the extended position 137.

Referring again to FIG. 4A, workpiece 114A is illustrated generallyresiding on the workpiece supports 126 of workpiece tray station 124A.In accordance with the invention, the elevator device 138 is operable tolinearly translate the elevator workpiece support 142 along the axis147, therein generally lifting and supporting the workpiece 114A fromthe workpiece tray station 124A, as illustrated in FIG. 4B. Once raisedfrom the plurality of workpiece supports 126 of tray station 124A, theworkpiece supports may be extended beyond the circumference 130 of theworkpiece 114A to the extended position 137 via the horizontaltranslation device 152, as illustrated in FIG. 4C. The workpiece 114Acan be then translated (e.g. raised or lowered along the axis 147) tothe characterization position 150, as illustrated in FIG. 4D, forcharacterization thereof via one or more characterization devices 154.

It should be noted that the characterization position 150 illustrated inFIGS. 4C and 4F in the present example is shown as being generally belowthe buffer position 128A. Thus, a single characterization device 154 canbe utilized for serial characterization of both workpieces 114A and114B. In such a case, the characterization position 150 can resideanywhere below the buffer position 128B. However, It should be furthernoted that additional characterization devices (not shown) may beimplemented, such that multiple characterization positions are possibleboth below and above buffer positions 128A and 128B, wherein workpieces114A and 114B may be characterized, and all such characterizationpositions and number of characterization devices are contemplated asfalling within the scope of the present invention.

The one or more characterization devices 154, for example, are operableto detect one or more characteristics associated with the plurality ofworkpieces 114 when each workpiece is at the characterization position150. The characterization devices 154 may comprise one or more of anoptical sensor 156, a camera 157 (illustrated in FIG. 3B), or variousother detection devices, wherein the one or more characterizationdevices are operable to detect the one or more characteristicsassociated with the plurality of workpieces 114 when each workpiece isat the characterization position 150 of FIGS. 4D and 4F. The opticalsensor 156, for example, is operable to detect a notch 158 in theworkpiece (illustrated in FIG. 6), as will be described in greaterdetail hereafter. The one or more characteristics may further comprise aposition of the workpiece 114 with respect to the elevator workpiecesupport 142, various indicia (not shown) associated with the workpiece,such as lot number, etc., or various other indicia or characteristicsassociated with the workpiece.

Referring again to FIG. 4D, the workpiece 114A can be removed from thealignment mechanism 122 after characterization thereof (e.g., via thefirst robot 110 or second robot 112 of FIGS. 1A, 1B, or 2), and theelevator device 138 can then generally lift and support the workpiece114B from the plurality of workpiece supports 126 of workpiece traystation 124B, as illustrated in FIG. 4E. Once raised from the pluralityof workpiece supports 126 of tray station 124B, the workpiece supportsmay be likewise extended beyond the circumference 130 of the workpiece114B to the extended position 137 of FIG. 4F, and the workpiece 114B canbe then translated (e.g. lowered) to the characterization position 150for characterization thereof. The workpiece 114B may then be removedfrom the alignment mechanism 122 via the first robot 110 or second robot112 of FIGS. 1A-1B or FIG. 2 for subsequent processing.

In accordance with another exemplary aspect of the invention, asillustrated in FIG. 3B, the elevator device 138 is further rotationallycoupled to the base 132, wherein the alignment mechanism is operable toindividually rotate the plurality of workpieces 114 about the axis 147associated with the elevator shaft 140 of FIG. 5. For example, arotation device 160 such as a servo motor may be operably coupled to theelevator shaft 140, wherein the rotation device is operable to rotatethe elevator shaft about the axis 147 (e.g., illustrated as arcuatearrow 161 in FIG. 3B). The rotation device 160 of FIG. 5, for example,further determines a rotational position of the elevator shaft 140 (andthus, the workpiece 114), wherein the alignment mechanism 122 isconfigured to further determine a position of the notch 158 (illustratedin FIG. 3B), such as for alignment of the workpiece with respect to thealignment mechanism, via the rotation of the workpiece through abeamline 162 of the optical sensor 156. The determined position of thenotch 158 may be utilized to orient the workpiece 114 with respect tothe alignment mechanism 122 via further rotation of the elevator shaft,for example, for subsequent processing.

The characterization device 154 (e.g., the optical sensor 156 of FIG. 5)may be further utilized to determine a center 163 of the workpiece 114,as illustrated in FIG. 6, with respect to the rotational axis 147 of theelevator workpiece support 142 via an examination of an output from thecharacterization device during the rotation 161. For example, FIG. 7illustrates a plot 164 of a rotational position 165 (e.g., provided bythe servo motor of the rotation device 160) of the elevator shaft 140and elevator workpiece support 142 of FIG. 5 versus a sensor signal 166from the optical sensor 156, wherein the center 163 of the workpiece 114can be extrapolated from the output signal curve (sensor signal 166)indicating the passage of the notch 158 through the beamline 162 and aknowledge of the dimensions of the notch. Accordingly, an offset vectorvalue associated with the center 163 of the workpiece 114 can beprovided to the first robot 110 and/or the second robot 112 of FIGS. 1A,1B, and 2, wherein, in the present example, the second robot isconfigured to pick the workpiece 114 from the alignment mechanism 122based on the offset vector value, and wherein the workpiece is generallycentered with respect to the second dual support member 121 when it ispicked from alignment mechanism. The rotational position of theworkpiece 114 can be further determined from the sensor signal 166 ofFIG. 7, wherein the workpiece can be further rotationally aligned withrespect to the alignment mechanism 122 prior to being picked by thefirst or second robots 110 or 112 of FIGS. 1A, 1B, and 2.

Referring again to FIGS. 1A and 1B, in accordance with another aspect ofthe invention, the workpiece handling system 100 further comprises afirst load lock module 168 and a second load lock module 170 operablycoupled to the front end module 102, wherein the plurality of workpieces114 may be transferred in series or in parallel between the front endmodule and the first or second load lock modules. For example, a firstload lock chamber 171, a second load lock chamber 172, a third load lockchamber 173, and a fourth load lock chamber 174, are further provided,wherein in the present example, the first load lock module 168 comprisesthe first load lock chamber and the third load lock chamber, and whereinthe first and third load lock chambers are generally vertically stackedupon one another, as illustrated in FIG. 8. Further, in a similarmanner, the second load lock module 170 of FIGS. 1A-1B comprises thesecond load lock chamber 172 and the fourth load lock chamber 174,wherein the second and fourth load lock chambers are further generallyvertically stacked upon one another. It should be noted that the firstload lock module 168 illustrated in FIG. 8 can be further considered tobe representative second load lock module 170 of FIGS. 1A-1B, whereinsimilar features may be present in the first and second load lockmodules.

According to the present invention, each of the first, second, third,and fourth load lock chambers 171, 172, 173, and 174 are furtheroperable to support two or more workpieces 114 therein. Each of thefirst, second, third, and fourth load lock chambers 171, 172, 173, and174 comprise a first isolation valve 175 associated with the front endmodule 102, wherein the first isolation valve selectively fluidlycouples an internal volume 176 of the respective load lock chamber tothe internal environment 109 of the front end module. According to oneexemplary aspect of the invention, each respective internal volume 176of the first, second, third, and fourth load lock chambers 171, 172,173, and 174 is further generally separated into first and secondvolumes 177A and 177B, as illustrated in the exemplary first load lockmodule 168 FIG. 8. For example, a mechanical isolation plate (not shown)is generally disposed between the first and second volumes 177A and177B, wherein the first volume is configured to generally confine one ofthe plurality of workpieces 114A, and wherein the second volume isconfigured to generally confine another one of the plurality ofworkpieces 114B. The mechanical isolation plate (not shown), forexample, generally prevents cross-contamination between the first volume177A and the second volume 177B within each respective internal volume176.

The workpiece handling system 100 of FIGS. 1A-1B of the presentinvention further comprises a vacuum module 180 operably coupled to thefirst and second load lock modules 168 and 170, wherein the vacuummodule comprises a generally evacuated internal environment 181. Forexample, one or more high vacuum pumps (not shown) may be operablycoupled to the vacuum module 180, therein generally evacuating thevacuum module. Furthermore, each of the first, second, third, and fourthload lock chambers 171, 172, 173, and 174 comprise a second isolationvalve 182 associated with the vacuum module 180 (e.g., illustrated inFIG. 8 with respect to the first load lock module 168), wherein thesecond isolation valve selectively fluidly couples the internal volume176 of the respective load lock chamber to the evacuated internalenvironment 181 of the vacuum module.

The vacuum module 180 of FIGS. 1A-1B is further operably coupled to aprocessing module 184, such as an ion implanter 185 operable to form anion beam 186. The processing module 184, for example, may comprise anelectrostatic chuck 188 disposed therein, wherein the electrostaticchuck is configured to individually selectively support the one or moreworkpieces 114. The processing module 184 may further comprise aprocessing robot 190 configured to translate the electrostatic chuck 188through a process medium 192, such as the ion beam 186 from the ionimplanter 186 for implanting ions into the plurality of workpieces 114.The processing module 184 may further comprise a dosimetry system (notshown).

According to another aspect of the invention, the vacuum module 180, forexample, comprises a third robot 194 and a fourth robot 196 disposedtherein, wherein each of the third and fourth robots, for example, arecapable of multiple degrees of freedom including vertical, radial andazimuthal movements. As illustrated in FIG. 2, the third robot 194, forexample, comprises a first single-workpiece handling arm 198 operablycoupled thereto, and the fourth robot 196 comprises a secondsingle-workpiece handling arm 200 operably coupled thereto, wherein thefirst and second single-workpiece handling arms are each operable tosupport a single workpiece 114.

Accordingly, the workpiece handling system 100, as illustrated in FIGS.1A-1B, is selectively configured to transfer two or more of theplurality of workpieces 114 in parallel (e.g., illustrated as dashedarrows 204) as well as one at a time or serially (e.g., illustrated assolid arrows 206), based on a desired flow of the workpieces through thesystem. The first robot 110, for example, is configured to selectivelytransfer two or more workpieces 114 at a time between the workpiecetransport containers 106A and 106B, the alignment mechanism 122, and thesecond load lock module 170 via the first dual-workpiece handling arm116. The second robot 112 is further configured to selectively transferthe two or more workpieces between the workpiece transport containers106C and 106D, the alignment mechanism 122, and the first load lockmodule 168 via the second dual-workpiece handling arm 120. The seconddual-workpiece handling arm 120, for example, is further configured toserially pick workpieces 114A and 114B from the alignment mechanism 122(e.g., from the characterization position 150 of FIGS. 5D and 5F), andthen transfer both workpieces in parallel to the second load lock module170. For example, the flow of workpieces 114 through the system 100 canbe reversed to service workpiece transport containers 106C and 106D,wherein the first and second robots 110 and 112 generally exchangefunctions, and wherein the third and fourth robots 194 and 196 likewiseexchange functions, as will be appreciated by one skilled in the art.FIG. 1A, for example, illustrates a counter-clockwise flow 208 forservicing workpiece transport containers 106A and 106B, whereas FIG. 1Billustrates a clockwise flow 210 for servicing workpiece transportcontainers 106C and 106D.

In accordance with another aspect, the third and fourth robots 194 and196, for example, are operable to serially transfer one workpiece 114 ata time between the process module 184 and the respective first load lockmodule 168 and second load lock module 170. It should be noted that thefirst and second isolation valves 175 and 182 associated with each ofthe first, second, third, and fourth load lock chambers 171, 172, 173,and 174 are operable to open and close independently; Thus, twoworkpieces 114 residing within the first load lock chamber 171, forexample, may be pumped down to vacuum or vented while another twoworkpieces may be independently vented to atmosphere or pumped down tovacuum in the third load lock chamber 173 of the first load lock module168. Likewise, two workpieces 114 residing within the second load lockchamber 172, for example, may be pumped down to vacuum or vented whileanother two workpieces may be independently vented to atmosphere orpumped down to vacuum in the fourth load lock chamber 174 of the secondload lock module 170. Thus, in conjunction with the novel alignmentmechanism 122 of the present invention, serial operations such asalignment of the plurality of workpieces 114 and processing of theworkpieces through the process medium 192 may be performed while otherparallel (e.g., generally simultaneous) transfers of multiple workpiecesare concurrently performed elsewhere in the system.

As illustrated in FIG. 1A-1B, a controller 212 is further provided tocontrol sequencing of workpieces through the system 100 and to controlactivation, deactivation and overall coordination of mechanical andenvironmental operations during workpiece handling and processing. Forexample, the controller is configured to control the front end module102, the first and second load lock modules 168 and 170, the vacuummodule 180, the processing module 184, and all components andenvironmental operations associated therewith. Environmental operations,for example, may comprise control of vent and pump down operations foreach of the load lock chambers 171, 172, 173, and 174 and control of thevacuum environment 181 in the vacuum module 180. Mechanical operations,for example, may comprise instructing the alignment mechanism 122,workpiece transport containers 106, the first, second, third, and fourthrobots 110, 112, 194, and 196 and various other workpiece handling andcontrol of various mechanical devices associated with the system 100.The controller 212, for example, may comprise multiple individualcontrollers (not shown) associated with various components of thesystem, or may be a single controller for the whole system 100, and allsuch controllers are contemplated as falling within the scope of thepresent invention.

FIG. 9 illustrates another exemplary system 213 of the invention,wherein the first dual workpiece handling arm 116 associated with thefirst robot 110 comprises a first pair of articulated arms 214A and214B, wherein each of the first pair of articulated arms comprise afirst single support member 216 configured to support a single workpiece114. The second dual workpiece handling arm 120 associated with thesecond robot 112, for example, further comprises a second pair ofarticulated arms 218A and 218B, wherein each of the second pair ofarticulated arms comprise a second single support member 220 configuredto support a single workpiece 114. The first pair of articulated arms214A and 214B, for example, can be configured to individually (e.g., inseries) or concurrently (e.g., in parallel) transfer two or more of theworkpieces 114 between the workpiece transport containers 106A and 106B,the second load lock module 170, and the alignment mechanism 122, in asimilar manner as the first dual workpiece support member 116 of FIGS.1A-1B. Likewise, the second pair of articulated arms 218A and 218B ofFIG. 9, for example, can be configured to individually or concurrentlytransfer two or more of the workpieces 114 between the workpiecetransport containers 106C and 106D, the first load lock module 168, andthe alignment mechanism 122, in a similar manner as the second dualworkpiece support member 120 of FIGS. 1A-1B. FIGS. 10A and 10Billustrate several views of an exemplary robot 222. The first robot 110and/or second robot 112 of FIGS. 1A-1B, 2, and/or 9, for example, maycomprise the robot 222 shown in FIGS. 10A and 10B. As illustrated inFIGS. 10A and 10B, the robot 222 comprises articulated arms 224A and224B, wherein each articulated arm respectively comprises a singlesupport member 226A and 226B operably coupled thereto. Accordingly, therobot 222 is operable to translate the single support members 226A and226B independently or in unison, based on the desired transfer ofworkpiece(s) as discussed above.

In accordance with another aspect of the present invention, FIG. 11illustrates an exemplary timing diagram 300 for transferring a pluralityof workpieces (e.g., eight workpieces) in a workpiece handling systemassociated with an ion implantation system. The system 100 illustratedin FIGS. 1A, 1B, and 2, and the system 213 illustrated in FIG. 9, forexample, can be operated in accordance with the timing diagram 300 ofFIG. 11. In FIG. 11, an exemplary flow 301 of first and secondworkpieces (workpiece “A” and workpiece “B”, respectively) through thesystem is highlighted, wherein first hatching 302 depicts actsassociated both the first workpiece and second workpiece being performedconcurrently, second hatching 303 depicts acts associated with only thefirst workpiece (e.g., serially), and third hatching 304 depicts actsassociated with only the second workpiece (e.g., serially). It is notedthat acts performed on other workpieces are illustrated as having nohatching, and that such acts can be performed concurrently (in parallel)or in series with the acts associated with first and/or secondworkpieces Furthermore, a method 305 for transferring workpieces in asemiconductor processing system is illustrated in FIG. 12, wherein thetiming diagram 300 of FIG. 11 may be further referenced. It should benoted that while exemplary methods are illustrated and described hereinas a series of acts or events, it will be appreciated that the presentinvention is not limited by the illustrated ordering of such acts orevents, as some steps may occur in different orders and/or concurrentlywith other steps apart from that shown and described herein, inaccordance with the invention. In addition, not all illustrated stepsmay be required to implement a methodology in accordance with thepresent invention. Moreover, it will be appreciated that the methods maybe implemented in association with the systems illustrated and describedherein as well as in association with other systems not illustrated.

As illustrated in FIG. 12, the method 305 begins at act 310, wherein afirst workpiece and a second workpiece are generally concurrentlyremoved (e.g., removed in parallel) from a first workpiece transportcontainer by a first robot. The first and second workpieces are thengenerally concurrently placed on an alignment mechanism via the firstrobot in act 312. The first workpiece is then aligned and/orcharacterized in act 314. For example, the first workpiece is raisedfrom a first workpiece support of the alignment mechanism via anelevator device. The first workpiece is further vertically translated toa characterization position, wherein the first workpiece is generallycharacterized, such as determining a position of a notch in theworkpiece, identifying the workpiece, and/or determining a spatialorientation of the workpiece with respect to the alignment mechanism.The first workpiece is then removed from the alignment mechanism via asecond robot in act 316.

The second workpiece is then aligned and/or characterized in act 318.For example, the second workpiece is raised from a second workpiecesupport of the alignment mechanism via the elevator device and thentranslated to the characterization position, wherein the secondworkpiece is characterized. The second workpiece is then removed fromthe alignment mechanism via the second robot in act 320, wherein thesecond robot is now generally supporting the first and secondworkpieces. The first and second workpieces are placed into a first loadlock chamber in parallel in act 322 via the second robot, and the firstload lock chamber is generally evacuated in act 324.

In act 326, the first workpiece is removed from first load lock chambervia a third robot and placed in a process chamber (e.g., placed on anelectrostatic chuck in the process chamber). The first workpiece issubjected to a process medium, such as an ion beam associated with anion implanter, in act 328, wherein ions are implanted into the firstworkpiece. Once ion implantation is complete, the first workpiece isremoved from the process chamber via a fourth robot and placed in asecond load lock chamber in act 330. At least partially concurrent toact 330, the second workpiece is removed from the first load lockchamber and placed in the process chamber via the third robot in act332, wherein the second workpiece is implanted with ions in act 334.Once ion implantation into the second workpiece is complete, the secondworkpiece is removed from the process chamber via the fourth robot andplaced in the second load lock chamber in act 336. Thus, the first andsecond workpieces are serially transported from the first load lockchamber to the process chamber for processing by the third robot, andserially transferred from the process chamber to the second load lockchamber by the fourth robot.

In act 338, the second load lock chamber is vented to generallyatmospheric pressure, and the first and second workpieces are removedfrom the second load lock chamber in parallel via the first robot in act340. In act 342, the first and second workpieces are placed in a secondworkpiece transport container. As an alternative, it should be notedthat the first workpiece transport container and the second workpiecetransport container can be the same workpiece transport container.

Acts 310 through 342 can be further repeated for third and fourthworkpieces, fifth and sixth workpieces, etc., as illustrated in thetiming diagram 300 of FIG. 11. For example, FIG. 13 illustrates acontinuation of the method 305 of FIG. 12, wherein the third and fourthworkpieces are generally concurrently removed from the first workpiecetransport container by the first robot in act 344, at least partiallyconcurrently with act 322 of FIG. 12. The third and fourth workpiecesare then placed in parallel on the alignment mechanism via the firstrobot in act 346 of FIG. 13. The third workpiece is then aligned in act348 and removed from the alignment mechanism via the second robot in act350. The fourth workpiece is then aligned in act 352, and the fourthworkpiece is then removed from the alignment mechanism via the secondrobot in act 354, wherein the second robot is now generally supportingthe third and fourth workpieces. The third and fourth workpieces areplaced into a third load lock chamber in parallel in act 356 via thesecond robot, and the third load lock chamber is generally evacuated inact 358. In act 360, the third workpiece is removed from third load lockchamber via the third robot and placed in the process chamber via thethird robot. Ions are then implanted into the third workpiece in act362, and the third workpiece is removed from the process chamber via thefourth robot and placed in a fourth load lock chamber in act 364. Atleast partially concurrent to act 364, the fourth workpiece is removedfrom the third load lock chamber and placed in the process chamber viathe third robot in act 366, wherein the fourth workpiece is implantedwith ions in act 368. Once ion implantation into the fourth workpiece iscomplete, the fourth workpiece is removed from the process chamber viathe fourth robot and placed in the fourth load lock chamber in act 370.Thus, the third and fourth workpieces are serially transported from thethird load lock chamber to the process chamber for processing by thethird robot, and serially transferred from the process chamber to thefourth load lock chamber by the fourth robot.

In act 372, the fourth load lock chamber is vented to generallyatmospheric pressure, and the third and fourth workpieces are removedfrom the fourth load lock chamber in parallel via the first robot in act374. In act 376, the third and fourth workpieces are placed back in thefirst workpiece transport container or the second workpiece transportcontainer.

As illustrated in the timing diagram 300 of FIG. 11, various acts areperformed at least partially concurrently with other acts. For example,acts 348, 350, 352, 354, and 376 of FIG. 13 are performed at leastpartially concurrently with act 324 of FIG. 12. Further, acts 326, 328,330, and 332 are performed at least partially concurrently with acts 354and 358 of FIG. 13. Acts 318, 320, and 322 of FIG. 12, for example, canbe performed at least partially concurrently with acts 344, 346, and 372of FIG. 13, and further, acts 362, 364, 366, and 368 can be performed atleast partially concurrently with act 338. Further, as more workpiecesare processed, more acts may be concurrently performed, as illustratedin the timing diagram 300 of FIG. 11, and all such concurrencies arecontemplated as falling within the scope of the present invention.

Parallel processing of workpieces advantageously improves productivityof the system. For example, load lock chambers may operate in asequential manner such that at a given point in time one load lock isopen to the vacuum module, one load lock chamber is open to the frontend module, one load lock chamber is venting to atmosphere, and one loadlock chamber is pumping down to vacuum. Accordingly, each of the first,second, third, and fourth load lock chambers go through a sequencegenerally repetitively, recommencing the full cycle at generally equallyphased intervals.

Accordingly, the present invention provides for a reduced cost ofownership of the processing system (e.g., an ion implantation system) byefficiently transferring workpieces between atmospheric and vacuumenvironments. Although the invention has been shown and described withrespect to a certain preferred embodiment or embodiments, it is obviousthat equivalent alterations and modifications will occur to othersskilled in the art upon the reading and understanding of thisspecification and the annexed drawings. In particular regard to thevarious functions performed by the above described components(assemblies, devices, circuits, etc.), the terms (including a referenceto a “means”) used to describe such components are intended tocorrespond, unless otherwise indicated, to any component which performsthe specified function of the described component (i.e., that isfunctionally equivalent), even though not structurally equivalent to thedisclosed structure which performs the function in the hereinillustrated exemplary embodiments of the invention. In addition, while aparticular feature of the invention may have been disclosed with respectto only one of several embodiments, such feature may be combined withone or more other features of the other embodiments as may be desiredand advantageous for any given or particular application.

1. An alignment and buffering apparatus for determining an orientationof a plurality of workpieces, the alignment mechanism comprising: abase; a workpiece buffering device comprising a plurality of workpiecetray stations aligned generally vertically with respect to one another,wherein each workpiece tray station is operable to selectively support arespective one of the plurality of workpieces in a respective bufferposition; an elevator device operably coupled to the base, wherein theelevator device is operable to individually vertically translate each ofthe plurality of workpieces from the respective buffer position to acharacterization position and to rotate each respective workpiece aboutan axis associated therewith; and a characterization device associatedwith the characterization position, wherein the characterization deviceis operable to detect one or more characteristics associated with eachof the plurality of workpieces when each respective workpiece is at thecharacterization position.
 2. The alignment and buffering apparatus ofclaim 1, wherein each workpiece tray station comprises: a plurality ofworkpiece supports associated with a circumference of the plurality ofworkpieces; and a horizontal translation device operably coupled to theplurality of workpiece supports, wherein the horizontal translationdevice is operable to selectively radially translate the plurality ofworkpiece supports between a retracted position and an extendedposition, wherein the plurality of workpiece supports are operable tosupport the respective workpiece in the retracted position, and whereinthe respective workpiece is free to vertically translate with respect tothe plurality of workpiece supports in the extended position.
 3. Thealignment and buffering apparatus of claim 2, wherein the plurality ofworkpiece supports comprise two or more arcuate support members.
 4. Thealignment and buffering apparatus of claim 3, wherein the two or morearcuate support members each comprise an arcuate recess having a radiusassociated with the circumference of the plurality of workpieces,wherein at least a portion of the circumference of the respectiveworkpiece generally rests on the arcuate recess when the plurality ofworkpiece supports are in the retracted position, and wherein the two ormore arcuate support members are generally positioned beyond thecircumference of the workpiece when the plurality of workpiece supportsare in the extended position, therein generally permitting the elevatordevice to vertically translate the workpiece to the characterizationposition when the plurality of workpiece supports are in the extendedposition.
 5. The alignment and buffering apparatus of claim 2, whereinfor each workpiece tray station, the elevator device is operable togenerally lift the respective workpiece from the plurality of workpiecesupports when the plurality of workpiece supports are in the retractedposition, and wherein the elevator device is operable to verticallytranslate the workpiece beyond a plane of the plurality of workpiecesupports when the plurality of workpiece supports are in the extendedposition.
 6. The alignment and buffering apparatus of claim 1, furthercomprising a controller configured to control the workpiece traystations, elevator device, and characterization device.
 7. The alignmentand buffering apparatus of claim 1, wherein the characterizationposition is generally below at least one of the buffer positions.
 8. Thealignment and buffering apparatus of claim 1, wherein the elevatordevice comprises an elevator shaft operably coupled to an elevatorworkpiece support, wherein the elevator shaft is in linear slidingengagement with the base, and wherein the elevator workpiece support isconfigured to selectively support each of the plurality of workpieces.9. The alignment and buffering apparatus of claim 8, wherein theelevator shaft is further rotationally coupled to the base.
 10. Thealignment and buffering apparatus of claim 9, further comprising a motoroperably coupled to the elevator shaft, wherein the motor is operable torotate the elevator shaft about the axis.
 11. The alignment andbuffering apparatus of claim 10, wherein the motor comprises a servomotor, and wherein the servo motor is configured to determine arotational position of the elevator shaft with respect to the base. 12.The alignment and buffering apparatus of claim 1, wherein thecharacterization device comprises an optical sensor, wherein the opticalsensor is operable to detect the one or more characteristics of theplurality of workpieces when each workpiece is at the characterizationposition.
 13. The alignment and buffering apparatus of claim 1, whereinthe one or more characteristics comprise one or more of a notch in theworkpiece, a position of the workpiece, and an indicia associated withthe workpiece.
 14. An alignment and buffering apparatus, comprising: abase; a first workpiece tray station configured to selectively support afirst workpiece, therein defining a first buffer position; a secondworkpiece tray station configured to selectively support a secondworkpiece, therein defining a second buffer position, wherein the firstbuffer position and second buffer position are generally alignedvertically; and an elevator device operably coupled to the base, whereinthe elevator device is configured to selectively translate each of thefirst workpiece and second workpiece along an axis between therespective first buffer position and second buffer position and acharacterization position.
 15. The alignment and buffering apparatus ofclaim 14, wherein the elevator device comprises an elevator shaftcoupled to an elevator workpiece support, wherein the elevator shaft isin linear sliding engagement with the base along the axis, and whereinthe elevator workpiece support is configured to selectively individuallysupport each of the first workpiece and second workpiece.
 16. Thealignment and buffering apparatus of claim 15, wherein the elevatorshaft is further rotationally coupled to the base.
 17. The alignment andbuffering apparatus of claim 16, further comprising a motor operablycoupled to the elevator shaft, wherein the motor is operable to rotatethe elevator shaft about the axis.
 18. The alignment and bufferingapparatus of claim 17, wherein the motor comprises a servo motor. 19.The alignment and buffering apparatus of claim 16, wherein thecharacterization device is operable to detect one or morecharacteristics associated with the first and second workpieces wheneach respective first and second workpiece is at the characterizationposition.
 20. The alignment and buffering apparatus of claim 19, whereinthe characterization device comprises an optical sensor, wherein theoptical sensor is operable to detect the one or more visualcharacteristics of the first and second workpieces when the respectivefirst and second workpiece is at the characterization position.
 21. Thealignment and buffering apparatus of claim 20, wherein the one or morevisual characteristics comprise one or more of a notch in acircumference of the respective first and second workpiece, a positionof the respective first and second workpiece, and an indicia associatedwith the respective first and second workpiece.
 22. The alignment andbuffering apparatus of claim 21, wherein the position of the respectivefirst and second workpiece comprises one or more of a rotationalposition of the respective first and second workpiece with respect tothe base and a center of the respective first and second workpiece withrespect to the elevator workpiece support.
 23. The alignment andbuffering apparatus of claim 15, wherein the elevator workpiece supportcomprises a vacuum chuck operable to selectively grip each of therespective first and second workpieces.
 24. The alignment and bufferingapparatus of claim 14, further comprising a controller operable tocontrol the first and second tray stations, the elevator device, and thecharacterization device.
 25. The alignment and buffering apparatus ofclaim 14, wherein each of the first and second workpiece tray stationsrespectively comprise: a plurality of workpiece supports each having anarcuate recess defined therein, wherein a radius of the arcuate recessis associated with a circumference of the first and second workpieces;and a horizontal translation device operably coupled to the plurality ofworkpiece supports and the base, wherein the horizontal translationdevice is configured to selectively radially translate the plurality ofworkpiece supports with respect to the axis between a retracted positionand an extended position.
 26. The alignment and buffering apparatus ofclaim 25, wherein the arcuate recesses of the respective plurality ofworkpiece supports are configured to selectively engage at least aportion of the circumference of the respective first or second workpiecewhen the plurality of workpiece supports are in the retracted position,and wherein a distance between the arcuate recesses of the plurality ofworkpiece supports is greater than a diameter of the first and secondworkpieces when the plurality of workpiece supports are in the extendedposition, wherein the respective first or second workpiece is free tovertically translate with respect to the plurality of workpiece supportswhen the plurality of workpiece supports are in the extended position.27. The alignment and buffering apparatus of claim 26, wherein theelevator device is configured to selectively lift the respective firstor second workpiece from the respective first or second workpiece traystation when the respective plurality of workpiece supports are in theretracted position, and wherein the elevator device is furtherconfigured to selectively translate the respective first or secondworkpiece along the axis to the characterization position when theplurality of workpiece supports are in the extended position.
 28. Thealignment and buffering apparatus of claim 24, wherein characterizationposition is positioned generally vertically below one or more of thefirst and second buffer positions.
 29. A method for aligning andbuffering workpieces, the method comprising: providing an alignmentmechanism having first workpiece tray station, a second workpiece traystation, and a vertically-translating elevator device, wherein the firstworkpiece tray station is aligned generally vertically beneath thesecond workpiece tray station, and wherein each of the first and secondworkpiece tray stations comprise a plurality of workpiece supports;generally concurrently placing first and second workpieces on theplurality of workpiece supports associated with the respective first andsecond workpiece tray stations; raising the first workpiece from theplurality of workpiece supports of the first workpiece tray station viathe elevator device; vertically translating the first workpiece to acharacterization position via the elevator device; characterizing thefirst workpiece; removing the first workpiece from the alignmentmechanism; raising the second workpiece from the plurality of workpiecesupports of the second workpiece tray station via the elevator device;vertically translating the second workpiece to the characterizationposition; characterizing the second workpiece; and removing the secondworkpiece from the alignment mechanism.
 30. The method of claim 29,wherein generally concurrently placing first and second workpieces onthe plurality of workpiece supports comprises lowering the first andsecond workpieces onto the plurality of workpiece supports when theplurality of workpiece supports associated with both the first andsecond workpiece tray stations are in a retracted position.
 31. Themethod of claim 30, wherein the first workpiece is raised from theplurality of workpiece supports of the first workpiece tray station whenthe plurality of workpiece supports of the first workpiece tray stationare in the retracted position.
 32. The method of claim 31, wherein thecharacterization position is generally below the first workpiece traystation, wherein vertically translating the first workpiece to thecharacterization position comprises radially translating the pluralityof workpiece supports of the first workpiece tray station from theretracted position to an extended position, and translating the firstworkpiece between the plurality of workpiece supports of the firstworkpiece tray station to the characterization position.
 33. The methodof claim 30, wherein the second workpiece is raised from the pluralityof workpiece supports of the second workpiece tray station when theplurality of workpiece supports of the second workpiece tray station arein the retracted position.
 34. The method of claim 33, wherein thecharacterization position is generally below the first workpiece traystation, wherein vertically translating the second workpiece to thecharacterization position comprises radially translating the pluralityof workpiece supports of the first workpiece tray station and secondworkpiece tray station from the retracted position to an extendedposition, and translating the second workpiece between the plurality ofworkpiece supports of the first workpiece tray station and secondworkpiece tray station to the characterization position.
 35. The methodof claim 33, wherein the characterization position is generally betweenthe first workpiece tray station and the second workpiece tray station,wherein vertically translating the second workpiece to thecharacterization position comprises radially translating the pluralityof workpiece supports of the second workpiece tray station from theretracted position to an extended position, and translating the secondworkpiece between the plurality of workpiece supports of the secondworkpiece tray station to the characterization position.
 36. The methodof claim 29, wherein characterizing the first and second workpiecescomprises: respectively rotating the first and second workpieces aboutan axis of the elevator device; and determining one or morecharacteristics associated with the respective first and secondworkpieces during the respective rotation.
 37. The method of claim 36,wherein determining the one or more characteristics comprisesdetermining a rotational orientation of the respective first and secondworkpieces with respect to the alignment mechanism, an offset positionof the respective first and second workpiece with respect to the axis,and an indicia associated with the respective first and secondworkpieces.
 38. The method of claim 37, wherein determining therotational orientation of the respective first and second workpiecescomprises: providing an optical sensor having a beamline directed towarda circumference of the first and second workpieces when the first andsecond workpieces are at the characterization position; obtaining asignal from the optical sensor as the circumference of the respectivefirst and second workpiece passes through the beamline of the opticalsensor during the respective rotation thereof; and determining aposition of a notch in the circumference of the respective first andsecond workpiece based on the signal obtained from the optical sensorand a knowledge of dimensional information associated with the notch.39. The method of claim 38, further comprising: rotating the respectivefirst and second workpieces to a predetermined rotational position viathe elevator device based on the determined position of the notch. 40.The method of claim 38, wherein determining the offset position of therespective first and second workpiece with respect to the axiscomprises: determining a rotational position of the elevator device; andanalyzing the signal obtained from the optical sensor as thecircumference of the respective first and second workpiece passesthrough the beamline of the optical sensor during the respectiverotation thereof, and extrapolating an offset vector based on alinearity of the obtained signal and rotational position of the elevatordevice.